In order to increase the cost-effectiveness of production of solenoid actuators, in many cases, a magnet element of the actuator has utilised traditional ferrite magnets in lieu of the more powerful rare earth magnets. Given the scarcity of rare earth elements, the cost of producing magnetic products using such magnets is increasing.
The weaker magnetic field of a ferrite magnet when compared with a rare earth magnet does, however, pose problems for the construction of actuators. Reducing the magnetic strength of the magnets in turn reduces the applicable force on the plunger of an actuator, which reduces the magnetic hold and coil drive across the entire stroke of the plunger. This can have deleterious effects for applications where a strong and consistent stroke is required in order to have any specific effect.
Actuators for switching contactor arrangements are one such area in which the stroke force is critical, since a weaker stroke force can lead to electrical arcing between contacts and/or contact bounce, either of which can damage the switching contactor and cause faults over time.